Polymerization of alkyl vinyl ethers with catalyst based on dialkyl aluminum halide and water

ABSTRACT

High molecular weight amorphous, or only slightly crystalline, polymers of improved characteristics are obtained by polymerization of alkyl vinyl ethers using an improved catalyst system comprising the reaction product of a dialkyl aluminum halide and co-catalytic amount of water.

United States Patent Schultz Feb. 27, 1973 POLYMERIZATION OF ALKYL VINYLETHERS WITH CATALYST BASED ON DIALKYL ALUMINUM HALIDE AND WATERInventor: Herman S. Schultz, Easton, Pa.

Assignee: GAF Corporation Filed: May 17, 1967 Appl. No.: 639,015

US. Cl ..260/9l.l M, 117/161, 260/803 E, 260/91.l A

Int. Cl. ..C08i 3/38 Field of Search 260/91.l, 91.1 M, 91.1 A, 80.3 E

Reierences Cited OTHER PUBLICATIONS Seagusa et al., Chem. Abs., 62(1965) p. 4127a. Furukawa et al., Chem. Abs. 64 (1966) p. 12840f.Furukawa et al., Chem. Abs., 64 (1966) p. 12840h to p. l2841a.

Primary ExaminerHarry Wong, Jr. Attorney-Steven J. Baron, Walter C. Kehmand Samson B. Leavitt [5 7 ABSTRACT 11 Claims, No DrawingsPOLYMERIZATION OF ALKYL VINYL ETHERS WITH CATALYST BASED ON DIALKYLALUMINUM HALIDE AND WATER FIELD OF THE INVENTION consisting of thereaction product of organo aluminum 1o halides with a co-catalyticamount of water.

It is an object of this invention to provide a process for producinghigh yields of clear, high molecular weight, colorless, amorphous oronly slightly crystalline structurally homogenous polymers of alkylvinyl ethers which are particularly suitable for use in the pressuresensitive adhesives, coatings, and as processing aids and tackifiers inthe plastic and rubber trades. It is another object of this invention toprovide a new catalyst system for polymerizing alkyl vinyl ethers topolymers which have the above characteristics at industrially practicaltemperature ranges. It is a further object of this invention to providea process for polymerizing alkyl vinyl ethers with a catalyst systembased on an organo aluminum halide and water. Other objects andadvantages of this invention will become readily apparent hereinafter asthe description proceeds.

I have now discovered that the-above objects may be readily obtained byutilizing a process for polymerizing alkyl vinyl ethers with a catalystbased on an organo aluminum halide in the presence of a co-catalyticamount of water.

Thus, the instant invention may be more specifically defined as aprocess for preparing amorphous or very slightly crystalline polymersfrom alkyl vinyl ethers which comprises polymerizing an alkyl vinylether, wherein the alkyl radical contains from one to 20 carbon atomswith a dialkyl aluminum halide catalyst and a co-catalytic amount ofwater.

DESCRIPTION OF PREFERRED EMBODIMENTS The alkyl vinyl ethers which areherein contemplated for use in the instant invention are those whereinthe alkyl radical contains from 1 to 20 carbon atoms, preferably fromone to 12 carbon atoms. Said ethers may be depicted bythe generalformula RO-CI-I= CH wherein R represents the alkyl radical. Specificexamples of such ethers include, for instance:

methyl vinyl ether ethyl vinyl ether n-propyl vinyl ether isopropylvinyl ether n-butyl vinyl ether isobutyl vinyl ether t-butyl vinyl etherneopentyl vinyl ether hexyl vinyl ether ethyl hexy] vinyl ether octylvinyl ether isooctyl vinyl ether decyl vinyl ether cetyl vinyl etherdodecyl vinyl ether tridecyl vinyl ether hexadecyl vinyl ether stearylvinyl ether octadecyl vinyl ether 2-chloroethyl vinyl ethertrifluoroethyl vinyl ether eicosyl vinyl ether and the like, or mixturesthereof' The polymerization catalysts employed by the present inventionare reaction products of the class of compounds known as dialkylaluminum halides with water. The dialkyl aluminum halides may berepresented by the formula wherein R represents the same or differentalkyl radical containing from one to 20 carbon atoms and wherein Xrepresents a halogen atom, such as chlorine, fluorine, bromine oriodine, preferably chlorine. Moreover, mixtures of two or more of thesecatalysts may be used, if desired. Examples of specific catalysts whichmay be mentioned include for instance:

dimethyl aluminum bromide dimethyl aluminum chloride diethyl aluminumchloride diethyl aluminum bromide diethyl aluminum fluoride dipropylaluminum chloride dibutyl aluminum chloride diisobutyl aluminum chlorideethylisobutyl aluminum chloride dipropyl aluminum fluoride diethylaluminum iodide dihexyl aluminum chloride dioctyl aluminum chlorideethylpropyl aluminum bromide, and the like.

In general, the homo or copolymerization process involves adding acatalytic amount of the dialkyl aluminum halide catalyst componentfollowed by a cocatalytic amount of water to one or more substantiallyanhydrous alkyl vinyl ether monomers in solvent solution. However, theorder of addition is not critical, for example, the water may be addeddirectly to the anhydrous polymerization solution or through theintroduction of controlled amounts of wet solvent or monomer. Acontrolled partial drying of the wet solvent employing molecular sievesto remove some but not all of its water, is an alternative procedurethat may be used, if desired. In addition, the reverse process of addingthe alkyl vinyl ether monomer to this hydrocarbon solution of thecatalyst, prepared from the dialkyl aluminum halide and water in situ,may also be followed. The catalyst may be added in total or batchwiseduring the course of the polymerization. An especially useful embodimentis the addition of the prereacted product from the dialkyl aluminumhalide component and water, generally in a diluent, as the catalyst. Forthe preparation of the prereacted catalyst, it is preferable forconvenience of handling and catalyst uniformity to add a dilute solutionof water in a carrier such as 1 ,4-

' dioxane and/or a hydrocarbon to a dilute solution of the dialkylaluminum halide in a hydrocarbon beginning under cold temperatureconditions, i.e., 0C and lower. From the standpoint of the most optimumresults, the preferred catalyst system is one in which the catalystconcentration based on the amount of dialkyl aluminum halide ranges fromabout 0.02 to about 2.0 mole-%, most preferably from about 0.03 to about0.5 mole-% relative to the weight of the alkyl vinyl ether monomer.

The polymerization process may be carried out at temperatures rangingfrom about 30 to 60C, while temperatures of about -lC to about roomtemperature are preferred for alkyl vinyl ethers having an alkyl radicalof two or more carbon atoms and temperatures of about 30 to about +l0Care preferred for methyl vinyl ether.

The use of proper co-catalytic amount of water is critical to theinstant invention if the optimum polymerization results are to berealized. For example, for methyl vinyl ether and higher alkyl monomers,little if any product is obtained in the absence of water, whilenegligible polymerization occurs in the presence of too much water. Theamount of water required as a cocatalyst may be represented by acatalyst/water molar ratio which may range from about 1/1 to 30/1, andis preferably maintained from about 3/ 1 to 1.

As pointed out above, one of the preferred conditions is to employ aninert non-reactive solvent as a carrier for the alkyl vinyl ethermonomer (so that the reaction system, i.e., solution is a liquid at thebeginning of the polymerization reaction) in order to obtain thegreatest degree of conversion and polymer of the best and optimumproperties. The presence of the solvent or diluent acts as a moderatinginfluence during the polymerization and prevents undesirable sidereactions and heterogeneity of the product which could result due, amongother factors, to the exothermic nature of the polymerization. The useof such inert solvents or diluents in the polymerization of alkyl vinylethers is well known, but in the present reaction it is preferred toemploy an aliphatic hydrocarbon solvent, such as pentane, hexane,heptane, octane and the like, especially hexane or heptane. However,other inert solvents, for example, cyclohexane, aromatic hydrocarbons,i.e., benzene, toluene, xylene and the like or hydrogenated hydrocarbonssuch as chloroform or methylene chloride and ethers such as diethylether, dipropyl, dioxane, and the like, may also be used, if desired. Itshould be understood, of course, that an admixture of two or more of theabove mentioned solvents may also be employed. The concentration of thealkyl vinyl ether monomer in the inert solvent is generally maintainedat the 15 to 50 percent level. Moreover, in order to obtain the mostoptimum results, it is preferred to utilize these solvents in a highlypurified substantially anhydrous form.

The instant process affords high conversion of monomer to polymer, forinstance, conversion values are often over 90 percent. In general, theamorphous or only slightly crystalline homopolymer products may becharacterized by their physical properties of being colorless, tacky,tough and rubbery and of high molecular weight values.

The viscosity number of a polymer is related to its molecular weightaccording to the Mark-Houwink equation (see Makromoleculare Chemie, Vol.37, pages 187-197, 1960):

wherein [17] intrinsic viscosity and M molecular weight by measurementsin benzene. The viscosity number at 0.1 percent concentration is veryclose to the intrinsic viscosity. Thus,

visc. no. he: -1)/ wherein C grams of polymer per cc. solution, 1relative viscosity and [v7] visc. no. um C A particular important andvaluable aspect of the instant invention is the good control one hasover the polymerization process.

Recovery of the final product is easily accomplished by conventionalprocedures. For example, the process may be easily quenched with anexcess of a lower alcohol or methanolic ammonia or amines and thequenched catalyst residues removed by procedures including washing withwater and/or methanol. The polymer may then be recovered by anyconventional method.

The following examples are illustrative of the present invention and arenot to be regarded as limitative. It is to be understood that all parts,percentages and proportions referred to herein and in the appendedclaims are by weight unless otherwise indicated.

EXAMPLE I Eighty grams of heptane previously washed with concentratedsulfuric acid and refluxed over sodium were distilled from LiAlH. into aclean, dry polymerization vessel under nitrogen. Then 20 g. of isobutylvinyl ether, whose purification involved water washing, refluxing oversodium metal and several careful fractional distillations, weredistilled from LiAlH, into the reaction vessel under dry nitrogen. 0.02g. (0.1 wt. based on the monomer) of diethyl aluminum chloride inheptane was introduced at room temperature. Very little polymerizationoccurred over a 2 hour period. The solution was very slightly viscousand no exotherm was given off. Heptane containing 1.96 X 10' moles ofwater was added and a rapid exothermic polymerization ensued. The moleratio of catalyst to water was about 8/1. 1. A very viscous solutionformed. Three hours later the polymerization was quenched with 1 cc ofmethanol, diluted with heptane and water washed. The heptane wasstripped off under reduced pressure and the polymer was dried at 5060Cunder 5 mm pressure for 7 hours. 20 g. (about 100 percent conversion) ofthe homopolymer product was obtained. The product was a colorless, tackyelastomic material which exhibited a viscosity number at 0.1 percent intoluene of 4.07 and was shown to be amorphous by X-ray diffractionexamination.

Similar results may be obtained by replacing isobutyl vinyl ether withother alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether,butyl vinyl ether, hexyl vinyl ether, isooctyl vinyl ether, dodecylvinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether, eicosyl vinylether and the like, or by replacing diethyl aluminum chloride with othercatalysts such as dimethyl aluminum chloride, diethyl aluminum bromide,diethyl aluminum fluoride, dibutyl aluminum chloride, diisobutylaluminum chloride, diethyl aluminum iodide, dioctyl aluminum chloride,ethylpropyl aluminum bromide, and the like.

EXAMPLE 11 A polymerization vessel with a dry nitrogen atmosphere and amechanical stirrer was charged with 80 g. of purified heptane containingppm water and 20 g. of purified isobutyl vinyl ether distilled fromsodium sand. The catalyst to water mole ratio was about 4/1. 1. At C,0.02 g. (0.1 wt. based on the monomer) of diethyl aluminum chloride inheptane was added. A polymerization ensued with the formation of a veryviscous solution in which a maximum temperature of 28C was attained.After 1 hour, the reaction was quenched with 1.2 cc of methanol, dilutedwith heptane. Recovery of the product by solvent stripping and vacuumdrying yielded 19.3 g. (about 96.5 percent conversion) of a colorless,tacky, rubbery polymer. This product exhibited a viscosity number at 0.1percent in toluene of 4.74 and was shown to be amorphous by X-raydiffraction examination.

EXAMPLE III A polymerization vessel with a nitrogen atmosphere and amechanical stirrer was charged with 165 cc. of AMSCO commercial heptanepreviously dried by passing over a column of molecular sieves to about60 ppm of water and g. of purified, freshly distilled isobutyl vinylether. The catalyst to water mole ratio was about 2/ 1. 1. This solutionwas cooled to -lC and 0.1 wt. based on the monomer of diethyl aluminumchloride in heptane was added. A slow slightly exothermic polymerizationensued with a maximum temperature of 4C being attained after 5 minutes.A very viscous solution was formed, the reaction was continued with likeportions of the catalyst being added after the first and third hours.After 4 hours the polymerization was quenched with 2 cc. methanol,diluted with heptane, washed with water and methanol. Solvent strippingand vacuum drying yielded 19.5 g. (about 97.5 percent conversion) of acolorless, tacky, rubbery homopolymer.

Said homopolymer had a viscosity number at 0.1 percent in toluene of3.76 and was shown to be amorphous by X-ray examination.

EXAMPLE IV The polymerization procedure for the following experiments 1through 5 were carried out as a set at the same time under the sameconditions. The polymerizations were carried out in carefully cleanedbottles equipped with a perforated crown cap and a self sealing capliner. The bottles which were used had first been alternately evacuatedand filled with nitrogen on a vacuum manifold several times withintermittent wanning with a hot air gun. The bottle reactors were cappedin a dry nitrogen filled dry box (or glove box). Hypodermic syringeassemblies and other necessary equipment used during the reactionmanipulation were handled similarly. Into the aforementioned nitrogenfilled and capped reactor bottles there was introduced by way of ahypodermic needle, methyl vinyl ether which had previously been purifiedand dried over sodium. The technique for transferring the monomer to thereaction bottle involves vaporizing the monomer from the storage vesselthereof through a closed, initially evacuated system and condensing thereactor at a lower temperature (0 to l0C) through the aforementionedhypodermic needle which has been previously injected into the reactionvessels. Purified and dried toluene was then injected by way of ahypodermic needle. The latter was purified and dried over sodium ribbonand was taken from bottles which were capped similarly as the reactorbottles in a dry box and then pressured with dry nitrogen immediatelyprior to withdrawal into a hypodermic syringe. The ratio of methyl vinylether to toluene employed in all the reaction was 1 gm/l cc. Variouscalculated amounts of nitrogen blown water were injected into thereaction solution at -l0C using a micro syringe. The catalyst bottle andthe reactor were all equipped with a device which makes it possible tokeep a flowing nitrogen atmosphere over the crown caps and still injector remove reagent to or from a bottle with a hypodermic syringe in aclean essentially moisture and air free fashion. 0.50 mole-% diethylaluminum chloride based on the monomer was added to each reactor at 0Cwith immediate hand shalking of the reaction bottles. The reactionsreacted for 22 hours at 0C after which they were concluded by quenchingwith methanolic ammonia and the products were recovered. The results ofthese experiments are recorded in the following table:

TABLE I Qualitative Comments Catalyst/H O Visc. No. on Rate andViscosity Run No. Ratio Yield 0.1% benzene of Reaction Solution 1 nowater 21% 1.26 only slightly viscous in 5 hours added 2 5/1 100% 0.67viscous within 15 min. 3 2/1 99% 0.26 viscous in 15 min. 4 l/l 88.4%0.17 viscous in 15 min. 5 H2 23% no viscosity after 22 hours The resultsaptly demonstrate that in the absence of water, or in the presence oftoo much water, low yields are obtained, while co-catalytic amounts ofwater in the proper range yield over 95 percent of an amorphoushomopolymer.

EXAMPLE V This example was carried out at the same time and by exactlythe same procedure at 0C as Example IV, except that the diethyl aluminumchloride/water mole ratio is 5/ l and the mole-% diethyl aluminumchloride relative to methyl vinyl ether is 0.070. The yield after 22hours was 50.6 percent and the viscosity number is 1.38.

EXAMPLE Vl Example IV was repeated except that a catalyst was preparedshortly before use in the following polymerization by reacting diethylaluminum chloride in heptane with water in.l,4-dioxane in toluene at l0C initially and then warming to room temperature. The titer of thediethyl aluminum chloride in heptane is 0.0355 grams/cc. solution; thetiter of water in 1,4- dioxane is 0.0294 grams/cc. solution; and cc.toluene was present in the reaction bottle. The mole ratio of thediethyl aluminum chloride/water aluminum 10/ l. The polymerzation wascarried out at 20C at a methyl vinyl ether/cc. toluene ratio of l/l andusing 0.5 mole-% of the above prepared catalyst, the moles of catalystbeing calculated on the basis of the moles of ethyl aluminum dichlorideused in the preparation and relative to methyl vinyl ether. Reactionovernight gave a 97.5 percent yield of a product having a viscositynumber of 2.1 at 0.1 percent in benzene at 25C. The product is aform-stable coherent film former with rubbery character of moderatestrength. X-ray diffraction shows the film to be amorphous.

EXAMPLE VII The criticality of employing a co-catalytic amount of wateris shown in the following experiment:

A clean S-liter reaction vessel was heated with a hot air blower whileunder vacuum and then purged twice with dry nitrogen. Through a droppingfunnel (closed circuit to the reactor) 1,200 g. of dry heptane preparedby distilling from sodium dispersion were introduced. The heptane wascharged to the reactor so as not to contact air or moisture. Next, 300g. of isobutyl vinyl ether distilled from sodium dispersion and storedover sodium ribbon were introduced from a dropping funnel through aclosed circuit to the reactor. The reactor contents were kept initiallyat about l82lC by circulating water around the outside of the literflask. Next, 0.1 weight percent diethyl aluminum chloride (based on theweight of the monomer) was added from a syringe through a port equippedwith a self sealing rubber septum so as to exclude air and moisture. 130minutes later an additional 0.1 weight percent of diethyl aluminumchloride was added. The reaction was allowed to continue for anadditional 65 minutes. During the entire reaction, the temperatureranged from l8-2lC. A 275 ml. sample was then removed from the reactorand the reaction of the sample was then removed from the reactor and thereaction of the sample stopped by addition of 5 cc. of methanol.Conversion of the monomer to polymer was about 51.4 percent and thepolymer had a viscosity number of 2.2

To the remainder of the reactants in the 5 liter flask, 0.03 cc. ofwater was added. After 10 minutes the temperature rose to 27C and thecontents of the flask became very viscous. The reaction was allowed tocontinue for about 1 10 minutes at which time it was stopped by theaddition of 5 cc. of methanol. Conversion of the monomer to homopolymerwas about 99.7 percent. The homopolymer product exhibited a viscositynumber of 3.0 at 0.1 percent in toluene. Thus, the simultaneous rise intemperature along with the increase in viscosity of the reactionscoupled with the improvement in conversion and higher viscosity of theproducts, demonstrates the uniqueness and superiority of the instantinvention.

EXAMPLE VI" A clean, dry polymerization vessel was heated with a Bunsenflame under vacuum to remove the last traces of surface moisture.Nitrogen gas pre-purified by passing through a triethyl aluminum-heptanesolution and dry ice traps was then passed into the vessel. Eighty gramsof purified heptane and 20 g. of purified isobutyl vinyl ether weredistilled into the flask under nitrogen from LiAlH The polymerizationsolution was then transferred to a dry box and measured amounts of wetheptane and 0.1 weight percent (based on the weight of the monomer) ofdiethyl aluminum chloride were injected. After three hours thepolymerization was quenched with 10 cc. methanol, diluted with heptane,water washed and stabilized with a phenolic antioxidant. The heptane wasstripped off under reduced pressure and the polymer was dried at 5060Cunder 5 mm. pressure for 7 hours. The results of a series of runs withvarying water content is listed in the following table:

A reaction was carried out as in Example Vll, with isobutyl vinyl etherbut at a diethyl aluminum chloride/H O mole ratio of 8/1. The viscositynumber (0.1 percent, toluene) of the product was 6.2.

Various modifications and variations of this invention will be obviousto a worker skilled in the art and it is understood that suchmodifications and variations are to be included within the purview ofthis application and the spirit and scope of the appended claims.

I claim:

1. A process for the production of homopolymers of alkyl vinyl etherscomprising polymerizing an alkyl vinyl ether monomer, wherein the alkylradical contains from 1 to 20 carbon atoms by maintaining the monomer incontact at a temperature of from about 30C. to C. with about 0.2 toabout 2.0 mole based on the weight of said monomer, of a catalystconsisting of the reaction product of a di-alkyl aluminum halide of theformula:

wherein, R and R represents an alkyl radical of from 1 to 20 carbonatoms and x represents a halogen radical, and a co-catalytic amount ofwater ranging from about 1 to 30 moles per mole of said dialkyl aluminumhalide.

2. A process as defined in claim 1, wherein the alkyl vinyl ethermonomer is methyl vinyl ether.

3. A process as defined in claim 1, wherein the dialkyl aluminum halideis diethyl aluminum chloride.

4. A process as defined in claim 3, wherein the alkyl vinyl ethermonomer is methyl vinyl ether.

5. A process as defined in claim 4, wherein the temperature ranges fromabout 30C to +1 0C.

6. A process as defined in claim I, wherein the alkyl vinyl ethermonomer contains an alkyl radical of from two to 20 carbon atoms.

7. A process as defined in claim 6, wherein the temperature ranges fromabout -l 0C to 60C.

molar ratio of dialkyl aluminum halide catalyst to water ranges fromabout 3/1 to 15/1 11. A process as defined in claim 1, wherein anorganic hydrocarbon is employed as a solvent carrier for the alkyl vinylether monomer.

2. A process as defined in claim 1, wherein the alkyl vinyl ethermonomer is methyl vinyl ether.
 3. A process as defined in claim 1,wherein the dialkyl aluminum halide is diethyl aluminum chloride.
 4. Aprocess as defined in claim 3, wherein the alkyl vinyl ether monomer ismethyl vinyl ether.
 5. A process as defined in claim 4, wherein thetemperature ranges from about -30*C to +10*C.
 6. A process as defined inclaim 1, wherein the alkyl vinyl ether monomer contains an alkyl radicalof from two to 20 carbon atoms.
 7. A process as defined in claim 6,wherein the temperature ranges from about -10*C to 60*C.
 8. A process asdefined in claim 7, wherein the alkyl vinyl ether is isobutyl vinylether and the dialkyl aluminum halide catalyst is diethyl aluminumchloride.
 9. A process as defined in claim 1, wherein the dialkylaluminum chloride concentration is about 0.03 to about 0.5 mole-% basedon the weight of the monomer.
 10. A process as defined in claim 9,wherein the molar ratio of dialkyl aluminum halide catalyst to waterranges from about 3/1 to 15/1.
 11. A process as defined in claim 1,wherein an organic hydrocarbon is employed as a solvent carrier for thealkyl vinyl ether monomer.